Hot plate



Jan. 29, 1935. R. R. McLEOD 1,989,234

HOT PLATE Filed Dec. 19, 1932 INVENTOR.

Patented Jan. 29, 1935 UNITED STATES PATENT OFFICE 1989,28; HOT PLATE 7Robert Raymond McLeod, Oakland, Calif. Application December 19, 1932,Serial No. 647,895

4 Claims. (o1.126' 214) This invention is a hotplate and is speciallydirected to a hotplate for usewith coffee brewers and for other purposeswhere heat resistant glass utensils are used and a uniform and mediumheat ,5 is required. Where glassware is used in heating liquids, it isquite important that the entire surface of the heating medium be of auniform temperature to prevent as much as possible unequal expansion invarious parts of the glass utensil.

Hotplates as at present supplied, consist of two varieties, onein whichthe heat is applied directly to the utensil, and the other in which theheat is applied through an interposed plate. Wherethe heat is supplieddirectly from the unit, very un equal heating is provided as the hottestzone is usually directly over any point of heat, and in theconsideration of a gas burner, a great many points of intense heat areprovided, one for each point of flame and being'located at the tip ofthe 20 oxidizing cone, and as the different jets are of various lengths,even these tips do not all come within the same distance from theelement being heated. Where a plate is interposed between the flame andthe object being heated, a more uniform heat is provided, however, therewill be considerable variation in the temperature at different parts ofthe plate.

My invention contemplates a hotplate which is heated almost exclusivelythrough themedium of heated air and not by conduction or direct actionof the heating unit thereon.

The main object of the invention therefore, is to provide a hotplatewith a uniformly heated top throughout its entire area 'so that allparts of the top will be maintained at the same temperature.

Another object of the invention is to provide a hotplate which has aminimum of bodily contact with the supporting means so as to: minimizethe transference of heat by conduction to the hotplate.

A further object of the invention is to provide a hotplate withreplaceable grid, shield and hot top, and to provide these elements withretaining means to prevent rotation thereof so that the elements will bemaintained in relative position when in use.

A still further object of the invention is to provide a hot top and ashield which are identical in structure and therefore replaceable onefor the other.

Other objects and advantages of the invention will become apparent asthe following description is read on the drawing forming a part of thisspecification, and in which similar reference characters are used todesignate similar parts throughout the several views, .of which:

Fig. 1 is a plan view of the invention.

Fig. 2is a view similar to Fig. 1 except with the hot top and the shieldremoved and showing the grid in position.

Fig. 3 is a side elevation of the invention.

Fig. 4 is a section taken on line 44 of Fig.1..

Fig. 5 is a fragmentary side view. of the hot plate and shield.

- Fig. 6 is a fragmentary view'of the encompassing wall and flange withthe shield supported thereon. l I

The invention consists of a frame 10 provided with legs 11, the framehaving an opening 12 in the top and. a depending continuous wall 13encompassingthe opening 12, this depending vwall having an inwardlyturned flange 14 for support ing the various elements of the hot plate.This flange is provided with recesses 15 and depressions 16, threedepressions and three recessesbeing preferably provided, and beingequi-angularly spaced. The device may be provided with a burner- 1'7 ofany desired type or for utilizing any kind "of fuel, but shown as a gasburner. The device'may have the legs 11 omitted, and in this manner canbe placed directly over the burner of astandard gas or electric range,andis therefore not .limited to use only withaheating'unit. w y v A grid.18 is freely and 'removably supported on the flange 14, the'gridpreferably having three ears 19 which are. receivable within thedepressions 16, the tops of the ears being disposed below the topsurface 20 of the flange 14, the three ears providing three-pointsuspension and thereby preventing any tendency toward rocking. Thepurpose of this grid is to receive the heat from the heating unit andretain this heat, and tending to I provide more uniform heating of thehotplate.

The shield 21 is supported on the flange 14, this shield having aplurality of support members, the legs 22 and lugs 23, the legs 22 beingof sufficient width to span the depressions 16 but having only a smallcontact surface 24 on each side of the depression. The lugs 23 alsofunction as aligning members to prevent rotation of the shield and toretain the legs 22 in proper position relative to the depression 16 soas to maintain a minimum area of contact between the legs 22 and theflange 20, the lugs 23 being normally out of contact with the walls 25of the recesses 15, the recesses and depressions being so formed thatthe periphery 26 of the shield is retained out of contact but in closerelation to the wall 13 so as to prevent conduction of heat between theperiphery of the shield and the wall.

The top or hotplate 27 is formed identical to the shield 21 and isreplaceable therewith. The lugs 23 are received in depressions 28 formedin the top surface of the shield 21 adjacent the periphery and thesupport members 23 being of suflicient length so that when the lugs restin the depressions 28, the legs 22 will clear the top surface 29 of'theshield 27. The upper plate 27 also has depressions. 28'formed therein,the shield and the plate being identical in construction throughout.

A dead air space is provided between the shield 21 and the top plate 27,the encompassing-wall 13 fitting closely to, but not touching theperiphery of these two plates, the lugs 23 having a relatively sharpbottom edge and being comparatively narrow, thereby providing a minimumarea of bodily contact with the shield 21 so as to minimize thetransferenceiof heat by conduction to the hotplate. \Thegrid, shield and"hotplate are all freelyremovable from the frame, and are provided withhook receiving recesses 30 by which the individual elements may beremoved.

It will be noted that the hotplate .is heated almost exclusively bymeans of the interposed heated .air in thespace between thetwo plates,and that this space together .with the encompassing wall, practicallyforms a dead air space and inlthismanner, and:due to the fact that thereis substantially no heat transferred by conduction, the entire topsurface of the hotplate is main- .tained ata uniform temperatureirrespective of theamount of heat applied by. the heating unit.

The :periphery of the .plate being out of contact with the wall. and thesubstantially knife-like edgesof the -.lugs23 having a'very small amountof :contact prevents hot spots in the :hotplate.

Having-described .an operativedevice, it will be understood thatvariations "in' the construction andlarrangement of. parts which areconsistent with the appended claims may be resorted towithout'rdetracting'from thespirit orscopeof the .invention iorsacrificing :any "of the advantages thereof. I

I claim: l 1.. A hotplate comprising a frame having-a fiat top formedwith an opening vtherethrough and a depending wall about said openingterminating in an iintumed supporting flange provided with a pluralityof spaceddepressions and a plurality of spaced recesses, alternatelyarranged, a grid in said opening having radial ears supported in saiddepressions, and a shield having a flat top of less diameter than saiddepending wall and spaced therefrom, a plurality of legs arranged tospan said depressions depending from said shield, and a plurality oflugs dependent from said shield and arranged to enter said recesses.

2. A hot plate comprising a frame having a flat top formed with anopening therethrough and a depending wall about said opening terminatingin aninturnedv supporting *flange provided with a plurality of spaceddepressions anda plurality of spaced recesses, alternately arranged, apair -of flat-topped shields supported in superposed relation in saidopening of less diameter than said depending wall and spaced therefrom,each said a-shield having a plurality of supporting legs arranged tosupport the shield upon said flange, and a plurality-of lugsintermediate said legs, respectively, ofgreater lengths than said legsand terminating in knife edges, said lugs being engageable in saidrecesses-and adapted to support the uppermost shield upon the subjacentshield.

3. A hot plate comprising a frame having aflat top formed with anopening therethrough and a depending wall about said opening terminatingin:an inturned supporting flange provided with spaced recesses, a pairof superposed flat-topped shields-in said opening of less diameter thansaid depending wall and spaced therefrom, each said shield having aplurality of evenly spaced legs adapted to support the shield upon saidflange, each said shield having a plurality of evenly spaced lugsintermediate said legs, said lugs having greater lengths than saidlegsand terminating in knife-edges adapting .the lugs toenter said recessesand to support the upper shield upon the upper surface of the subjacentshield.

4. A hot platecomprisinga framehaving a flat .top formed with an opening.therethrough .and adepending wall about said opening terminating in-aninturned supporting flange. provided with spaced recesses,.a pair ofsuperposed shieldssupported in superposed relationin said opening oflessdiameter than said depending wall and. spaced therefrom, each saidshield having .a plurality of depressions .in its uppersurfacagaplurality of legs depending from each saidshield to support thelowermostshield uponsaid flange, and a plurality of lugs on.saidshieldspacedbetween said legsand arranged to enter said flange-recesses and saidshieldedepressions inthe lowerand upper positions of the shields,respectively, said lugs having knife-edges at their ends.

ROBERT RAYMOND .McLEOD.

